When Christopher Grotke answered a late-night knock on the door, he did not expect to find the deputy sheriff on his doorstep serving notice that he was being sued. Nor was he prepared for the charge: libel.

Someone had posted a comment on his citizen-journalism website, iBrattleboro.com, stating that a woman in Brattleboro, Vt., was having an extramarital affair. The accused woman then sued Mr. Grotke and his website cofounder for failing to edit or delete the comment.

The blogging community increasingly is subject to lawsuits and threats of legal action running the gamut from subpoenas to cease-and-desist notices. Since blogging became popular in about 2004, there have been 159 civil and criminal court actions involving bloggers, according to the nonprofit Media Law Resource Center (MLRC) in New York. Seven cases have resulted in verdicts against bloggers, with cumulative penalties totaling $18.5 million. Many more legal actions never result in trial.

“There is a chilling effect of a cease-and-desist letter or a legal threat that claims an aspect of a blogger’s work could lead to liability, even when those claims are not well grounded,” says Kurt Opsahl, a senior staff attorney at the Electronic Frontier Foundation (EFF), a nonprofit in San Francisco that defends digital rights.

Bloggers faced with legal threats often deem it easier to remove potentially offensive content rather than undertake the difficulty and expense of defending themselves, he adds.

Abroad, more than 60 bloggers arrestedBloggers face much bigger threats overseas, particularly if they criticize governments or point to human rights abuses.

Since 2003, 64 bloggers have been arrested around the world – with Egypt, China, and Iran initiating more than half of those arrests, according to the World Information Access Report, published last month by the University of Washington. By contrast, the United States has arrested two in that period.

Still, online commentators face risks in the United States.

“In the developed world, bloggers can be punished through lawsuits,” writes Philip Howard, a communications professor at the University of Washington, in an e-mail.The number of lawsuits is growing, says Robert Cox, president of the Media Bloggers Association (MBA), a US-based group devoted to protecting citizen journalists. “As blogging expands and more people are aware of it, the lawyers are not far behind.”

No one is suggesting that bloggers should have free rein to publish whatever they want.

“If you’re slandering, you can be sued whether you have a blog or not,” says Mr. Cox, a blogger himself. “You’re not immune to defamation charges ... just because you’re a citizen speaking your mind.”

Who should educate the bloggers?There is no consensus, however, on how best to make bloggers aware of their legal responsibilities.

Many lawyers expect bloggers to figure it out themselves.

“If you’re going to be responsible enough to manage a site where people post such things, you should be able to detect when things are defamatory and take them down,” says Margot Stone, the lawyer for the woman who sued Grotke. “The problem is that technology is outpacing the ethical responsibilities. People haven’t thought through the ethics of all this.”

Online communities as well as media activists and lawyers are pushing to ensure that bloggers are aware of their legal rights and responsibilities.

“We’re coming up with a product that covers defamation, copyright, privacy violations – the same protections as newspapers – for bloggers,” says the group’s Mr. Cox. MBA members will receive a hefty discount on the insurance package, due to be launched at the end of this month. The cheapest coverage for a solo blogger will be $540 a year.

But some bloggers resist the idea.

“I don’t have the money for that kind of thing,” says Kathleen Seidel, a New Hampshire-based blogger who was subpoenaed this spring in connection with another lawsuit against vaccine manufacturers that she had written about on her blog.

Having written several posts about litigation and completed two legal courses at the local community college, Ms. Seidel was able to deflect legal threats against her blog and successfully composed a motion to quash the subpoena.

Grotke, too, was able to convince a Vermont court to dismiss libel charges.

Many bloggers, however, aren’t so fortunate, which is why the online community is searching for ways to protect them. “The effect of intimidation is a real one,” Seidel says.